Аннотация:This article tries to assess the energy import diversity of the Republic of Korea and Japan, which are 2 of the biggest energy importing countries and have a higher level of dependency on energy import. Diversity in energy import is one of the major concepts composing the concept of energy security, which is considered as the basement of national energy policy in those countries. In order to assess the energy import diversity, we employ Shannon’s diversity index that is one of the widely used diversity indexes in the field of energy diversity and mea- sure the index from 2000 to 2015. The import diversity indexes of major fossil fuel resources, which are oil, natural gas, and coal, show different levels and trends in both countries. The composite diversity index of energy import of the countries has improved from 2009 and it has been stimulated by the import diversity index of natural gas. Russian natural gas has contributed to the increase in the diversity index of natural gas and it is expected that the diversity index of natural gas could be increased more in the future by the increased volume of imported Russian natural gas. Meanwhile, it is still necessary for both countries to improve oil import diversity, despite the decreas- ing share of oil in their TPES considering the importance of oil in the industries of the countries and very high dependency of oil imports on the Middle East.